I have two primary steeds .. a ~2006 K2 roadbike with a Truvative crank (with Truvative's wierd bottom bracket), and a ~2006 no-longer-in-business mountain bike, aluminum frame, deore bottom bracket and crank. I am amazed how smooth the old JIS/square taper seems. I beat the poo out of the mtb, and it just goes and goes. The K2 on the otherhand, is my daily driver. It seems as though the crank is constantly coming loose (enough so that under a full out sprint the chain grinds the front derailer occasionally), and has much more movement in it.

So -- Is there something I can do to keep the crank bolt from loosening? Should I just replace it with a decent square taper bottom bracket/crank?